Frame airline before start of hijack (4)
I believe the answer is:
sash
'frame' is the definition.
(I know that sash is a type of frame)
'airline before start of hijack' is the wordplay.
'airline before' becomes 'sas' (I can't explain this - if you can you should believe this answer much more).
'start of' indicates taking the first letters.
The first letter of 'hijack' is 'h'.
'sas'+'h'='SASH'
Can you help me to learn more?
(Other definitions for sash that I've seen before include "Window frame; silk band" , "Framework to hold the panes of a window" , "Ribbon worn over the shoulder" , "Window frame - shoulder band" , "(Uniform) strip; window-frame" .)